Cathode ray tube



Ma 25 1943. R I

Y I R. H. GEO G ErAL 2 319 11 GATHODE RAY TUBE Filed June 28, 1941 2 Shee ts-Sheet 1 I INVENTORS ATTORNEY y 3- R. H. GEORGE arm. 2,319,311

' cmnonm an TUBE Filed June 28, 1941 2 Sheets-Sha et 2 INVENTORS -xww ATTORN EY Patented May 25, 1943 CATHODE RAY TUBE Roscoe H. George and Wilfred M. Hesselberth,

West Lafayette, Ind., assignors to Radio Corporation of America, a corporation of Delaware Application June as, 1941, Serial No. 400,192

8 Claims.

This invention relates to a cathode ray tube and more particularly to a tube wherein the physical size, and particularly the over-all length, has been reduced as compared with the dimensions of the screen area.

In conventional cathode ray tubes, the electron gun structure is mounted in the neck of the tube with the terminals for the various electrodes brought out principally at the small end of the tube through a glass press. In some instances one or more electrode terminals are brought out at the side of the tube but in most instances the terminals for the electrodes are arranged in a manner similar to an ordinary vacuum tube.

When such a construction is used, the neck portion of thetube assumes considerable longitudinal dimensions and the over-all length of the tube is appreciable inasmuch as a certain spacing between the deflecting electrodes and the screen must be maintained in order to produce the desired deflection sensitivity and in order that the beam may be deflected a desired amount. A cathode ray tube when so constructed has considerable over-all length as compared with the diameter of the viewing screen on the inside surface of the large end of the tube.

In certain types of work, particularly where relatively large screens are necessary, this excessive over-all length of a conventional cathode ray tube is objectionable inasmuch as it requires rather bulky housings for the apparatus and if shert leads are to.be used the screen may be considerably removed with respect to the actual apparatus which is used in connection with the cathode ray tube..

One purpose of the present invention, therefore, residesin the design of a cathode ray tube in which the over-alllength is materially reduced as compared with conventional cathode ray tubes having the same or similar screen area.

Another purpose of the present invention resides in a cathode ray tube in which the terminals for the various electrodes are brought out through the side of the tube, the terminals-preferably lying in a common plane normal to the geometrical axis of symmetry of the tube.

Still another purpose of the present invention resides in the provision of means whereby the cathode ray beam generated in such a tube may and in which the conventional glass press or seal is omitted.

Still another purpose of the present invention resides in the provision of means positioned within the tube whereby the permeability of the deflection yoke may be materially increased when electromagnetic deflection is used.

A further purpose of the present invention resides in the provision of electrode terminals positioned about the tube in such a manner that an annular socket may be used in cooperation with the terminals. 7

Still a further purpose of the'present invention resides in the construction of a cathode ray tube in which the tube may be readily removed from the socket'without in any way disturbing any of the connections or without the necessity of removing the electro-magnetic deflection yoke where magnetic deflection is used.

Still other purposes and advantages, of the present invention will become more apparent to those skilled in the art from reading the follow- .ing specifications, particularly when considered in connection with the drawings wherein;

Fig. 1 shows a longitudinal section ofone of the present invention.

Fig. 2 shows a sectional view lines 2-2 of Fig. 1.

Fig. 3 shows a sectional View taken lines 3-3 of Fig. 1.

Fig. l-shows a modification of the present invention for electrostatic deflection.

Fig. 5 shows a section of Fig. 4 taken along the lines 5-5.

In Fig. 1 is shown a complete cathode ray tube together with an electromagnetic deflection yoke and a socket in cooperation with the tubeterminals. .The cathode ray tube includes an envelope l0 having an enlarged end portion l2, the inside surface of the enlarged end portion being coated with a fluorescent or luminescent coating M. The purpose of this coating is well known to those skilled in the art. In the oppositeend of the cathode ray tube are included the various elements necessary to generate the cathode ray beam and to deflect the cathode ray beam across the target screen it. These elements include a form taken along the along the cathode heater IS, a cathode l8, a control cylinder or grid 29, a first anode 22 and a second anode 24. When proper potentials are applied to these electrodes and elements, a focused cathode ray beam will be produced. I V

For deflecting the cathode ray beam in mutually perpendicular directions, an electromagnetic system is provided which includes a magnetic deconductors are flection yoke 23 having poles 25. Positioned upon each of the poles are electromagnetic coils 26. These coils are arranged in pairs and when energized by appropriate voltages will cause the desired deflection of the generated cathode ray beam. In order to increase the deflection sensitivity of the cathode ray tube and in order to increase the permeability or decrease the reluctance, magnetic pole pieces 28 are provided within the tube. These pole pieces, as well as the magnetic part of the deflection yoke are preferably constructed of thin laminated elements in order to reduce the hysteresis losses. The various laminations of the pole pieces and/or of the deflection yoke may be separated by very thin pieces of mica or the laminations may be coated with magnesium oxide in order to' increase the resist ance through the laminations.

The four separate pole pieces 23 are mechanically attached to the second anode 24 by means of a plurality of rivets 3!]. The pole pieces which are attached to the second anode are supported on the screen side of the first anode, as shown in the drawing, with the second anode adjacent the first anode and this support may be by means of mica discs or washers.

The first anode 22 is also supported within the neck portion of the tube It! by means of mica discs 32 as is also the control electrode 20.

In order that electrical connections may be made to the various elements within the tube, provided. These conductors emerge preferably in a common plane normal to the axis of the tube and this plane is located in the vicinity of the section line 3-3 of Fig. 1.

The terminals ar indicated as 34, 36, 33, 40 and 42. In order that these terminals may be readily connected to the external circuit, a socket 44 is provided towhich are attached spring lugs for cooperation with each of the terminals associated with the elements within the tube. The heater I6 is supported in proper position by means of the conductors 34 and 36 and these. conductors pass between adjacent pole pieces of a magnetic structure. The second anode is cut away as indicated in Figures 2 and 3 in order to afford the necessary spacing between elements. The cathode IB is preferably supported by the heater element and is so supported as to be in good thermocontact therewith. Furthermore, mica discs l9 may be used to maintain the cathode in proper position within the control cylinder 29. The control grid 20, as stated above, is supported in position by means of the mica discs 32 and a conductor 38 affords a means whereby potentials from an external circuit may be applied to the control electrode. The conductor 38 in passing longitudinally along the tube passes between the adjacent pole pieces as do the conductors for the heater. The first accelerating anode 22, as stated above, is supported in proper position by means of the mica discs or annular members 32 and electrical connection is made to the first anode through conductor 42. The second anode 24 has potential applied thereto by means of conductor 48 which passes through the rivet perforations in one of the pole pieces and, inasmuch as the pole pieces are operated at second anode potential, no insulation between the conductor Q5 and the pole pieces need be provided. In fact, the conductor to may act as one of the rivets for maintaining one of the pole pieces attached to the second anode.

In order to shield the various conductors which I are positioned within the tube, a shield member 46 is provided. This shield may be supported within the tube by means of mica discs 41 and, in addition, it may be connected to the second anode by a short length of wire (not shown). In view of the use of the shield 46, the proximity of the conductors with respect to the produced cathode ray beam does not in any way afiect the operation of the tube. Furthermore, the shield prevents any interaction between conductors which are secured to the socket and the cathode ray beam.

From the foregoing it may be seen that a cathode ray tube of radically different design has been produced which results in extreme compactness and which has considerable deflection sensitivity. Furthermore, through the construction of the tube above described it is readily possible to replace the tube or to make exchanges in tubes by merely withdrawing the tube from the socket 44 and, in this manner, the deflection yoke is in no way disturbed. Inasmuch as all of the conductors are brought out through the side of the tube, the over-all length of the tube is materially reduced since the usual socket terminals and glass press are omitted. Because of the particular internal construction of the tube it is possible to have all of the terminals for the elements terminated in a common plane which results in the possibility of using a socket of simple and convenient design.

While the tube described With respect to Figures 1, 2 and 3 is for use in electromagnetic deflection circuits, the tube shown in 4 and 5 may be used where electrostatic deflection is employed. In certain respects this tube is similar to the tube shown in Figures 1, 2 and 3 except that the magnetic pole pieces are omitted and instead thereof electrostatic deflection plates are employed.

Th heater I6 is supported by and is supplied with energy along conductors 34 and 36'. The control electrode 20' is supported by mica discs as in Fig. 1 and is supplied with energy by conductor 38'. The first anode 22' is also supported by mica discs and is supplied with energy by conductor 42'. The second anode 24 which is supported in proper position by a mica disc and is supplied with energy by conductor 40.

As stated above, in lieu of magnetic pole pieces, electrostatic deflection plates are provided. These plates are arranged in pairs as is conventional and are positioned in tandem relationship. One pair of plates 48 are for deflecting the oathode ray beam in one direction, for example, vertically, whereas the other pair of plates 49 are for deflecting the cathode ray beam in another direction, for example, horizontally. The plates 48 are supplied with deflection potentials by means of conductors 50 while the other pair of deflection plates are supplied with deflection potentials by means of conductor 52. Both pairs of deflecting plates, as may be seen from the drawings, are positioned at an angle to the axis of the tube rather than parallel thereto as is the usual practice. This is done to increase deflection sensitivity.

All of the conductors for supplying energizing potentials or deflection voltage variations to the various elements of a cathode ray tube emerge through the wall of the cathode ray tube in a common plane as indicated in Figures 4 and 5. Accordingly, it is possible to use a socket 44 similar to the socket used in the tube shown in Fig. 1.

An electrostatic shield 54 is also provided and this shield is preferably operated at a second anode potential. Accordingly, the shield 54 is connected to the conductor 40 (this connection not shown in the drawing) and the shieldis supported in proper position by means of the mica disc 56.

With this construction the cathode ray tube having the advantages of the tube shown in Fig. 1, it is possible to deflect the cathode ray beam electrostatically. In the construction shown in Fig. 4 the over-all length of the tube is materially reduced as is the case with the tube shown in Fig. 1 and, furthermore, the tube may be as conveniently replaced even though electrostatic deflection is used.

Although the tubes shown in Figures 1 and 4 are described as cathoderay tubes in which a f.

fluorescent or luminescent screen is used, it is entirely possible to use a gun structure such as that shown and described in any other kind of a cathode ray tube such as a television transmitting tube.

ing potentials to the electrodes may be of appreciable physical'size, these conductors offer considerable support and alignment in so far as the electrodes are concerned so that it is possible to dispense with some of the mica discs. The use of the discs is preferable, however, inasmuch as they assist in preventing mis-alignment of one or more of the elements.

Various alterations and modifications of the present invention may become apparent to those skilled in the art and it is desirable that any and all such modifications and alterations be considered within the purview of the present invention except as limited by the hereinafter appended plane through the side wall of the cylindrical portion of the tube envelope in a region intermediate the location of the second anode member and the junction of the conical and the cylindrical portions of the tube, so that energizing potentials may be applied to the various elements.

2. A cathode ray tube having a conical envelope portion and a, substantially cylindrical neck portion attached to the small end of the conical portion and positioned coaxial therewith, said neck portion enclosing means adapted to generate a narrow focused cathode ray beam, said means including a cathode, control electrode, first anode and second anode elements, means including insulating discs for positioning and retaining the elements in a predetermined position, and a conductor electrically connected to each of the elements, each of said conductors extending in substantially a common transverse plane through the side wall of the cylindrical portion of the tube envelope in a, region intermediate the location of the second anode member and the junction of the conical and the cylindrical portions of the tube, so that energizing potentials may be applied to the various elements.

3. A cathode ray tube having a conical envelope Inasmuch as conductors which supply energiz- Cir portion and a substantially cylindrical portion having one end closed and attached at the other end to the small end of the conical portion and positioned coaxial therewith, means in said cylindrical portion adapted to generate a focused cathode ray beam, said means including a cathode, control electrode, first anode and second anode elements, means for positioning and retaining the elements in a predetermined position, and a conductor electrically connected to each of the elements, each of said conductors extending in substantially a common transverse plane through the side wall of the cylindrical portion of the tube envelope in a region intermediate the location of the second'anode member and the junction of the conical and the cylindrical portions of the tube, so that energizing potentials may be applied to the various elements.

4. A cathode ray tube having a conical envelope portion and a substantially cylindrical neck portion having one end closed and attached at the other end to the small end of the conical portion and positioned coaxial therewith, means in said neck portion adapted to generate a focused cathode ray beam, said means including a cathode, control electrode, first anode and second anode elements, means including a plurality of insulating discs for positioning and retaining the elements in a predetermined position relative to each other, and a conductor electrically connected to each of the elements, each of said conductors extending in substantially a common transverse plane through the side wall of the cylindrical portion of the tube envelope in a region intermediate the location of the second anode member and the junction of the conical and the cylindrical portions of the tube, so that energizing potentials may be applied to the various elements.

5. A cathode ray tube having a substantially cylindrical envelope portion closed at one end, means in said cylindrical portion adapted to generate a focused cathode ray beam, said means including a cathode, control electrode, first anode and second anode elements, a plurality of electromagnetic pole pieces included in the cylindrical portion, means for positioning and retaining the elements as well as the pole pieces in a predetermined position, and a conductor electrically connected to each of the elements and extending through the side of the cylindrical portion in a plane positioned substantially normal to the axis of the cylindrical portion, the conductors extending in an axial direction'through the plane of the pole pieces, whereby energizing potentials may be applied to the elements and whereby the tube may be removed from a socket member without disturbing any of the surrounding apparatus.

6. A cathode ray tube having a substantially cylindrical envelope portion closed at one end and composed of insulating material, means in said cylindrical portion adapted to generate a focused cathode ray beam, said means including a cathode, control electrode, first anode and second anode elements, a plurality of electromagnetic pole pieces included in the cylindrical portion, means for connecting the pole pieces to the second anode element, means for positioning and retaining the elements as well as the pole pieces in a predetermined position, and a conductor electrically connected to each of the elements and extending through the side of the cylindrical portion in a plane positioned substantially normal to the axis of the cylindrical portion and located on the side of the pole pieces opposite the side on which the elements are located, the conductors extending in an axial direction through the plane of the pole pieces and between the individual pole pieces, whereby energizing potentials may be applied to the elements and whereby the tube may be removed from the socket member without disturbing any of the surrounding apparatus.

'7. A cathode ray tube having a substantially cylindrical envelope portion closed at one end, means in said cylindrical portion adapted to generate a focused cathode ray beam, said means including a cathode, a control electrode, first anode and second anode elements, a plurality of pairs of beam deflecting plates positioned in cylindrical portion, means for positioning and for retaining the elements and the deflecting plates in a predetermined position, and a conductor electrically connected to each of the elements and to each of the deflecting plates, said conductors extending through the side of the cylindrical portion in a plane substantially normal to the axis of the cylindrical portion whereby energizing potentials may be applied to the elements and to the deflecting plates.

8. A cathode ray tube having a substantially cylindrical envelope portion closed at one end, means in said cylindrical portion adapted to generate a focused cathode ray beam, said means including a cathode, a control electrode, first anode and second anode elements, a plurality of pairs of beam deflecting plates positioned in cylindrical portion, means including insulating members for positioning and for retaining the elements and the deflecting plates in a predetermined position relative to each other, and a conductor electrically connected to each of the elements and to each of the deflecting plates, said conductors eX tending through the side of the cylindrical portion in a plane positioned substantially normal to the axis of the cylindrical portion and located intermediate the ends thereof whereby energizing potentials may be applied to the elements and to the deflecting plates.

ROSCOE H. GEORGE. WILFRED M. HESSELBERTI-I. 

